The present invention relates to a magnetic head element and magnetic head for a magnetic recording/reproducing apparatus for recording or reproducing information on/from a magnetic medium.
The present invention, in particular, relates to a magnetic head element and magnetic head suitable for a camera having a magnetic head for recording or reproducing information on/from a magnetic storage portion formed on a film, a camera pressure plate having the magnetic head element or magnetic head, and a camera having the pressure plate.
Recently, a camera that uses a film having a magnetic storage portion and can record or reproduce information such as photographing conditions and date on or from the magnetic storage portion has been developed and introduced commercially. Information about the camera includes the number of exposures, shutter speed, f number, exposure correction value, date, title, and the like. The camera incorporates a magnetic head for recording or reproducing these pieces of information on or from a magnetic storage portion of a film.
Recording of these pieces of information on a film allows an easy film change, makes developing/printing processing consistent, and finds application to multimedia equipment using photographic images upon processing them by computers using film scanners. This technique is therefore regarded as a promising technique.
FIG. 9 shows a schematic arrangement of a camera capable of recording or reproducing magnetic information. Referring to FIG. 9, reference numeral 100 denotes a camera body; 101, a lens; 102, a film cartridge loaded in the camera body; and 103, a film fed from the film cartridge 102. FIG. 9 shows a state in which the film 103 is wound around a spool 105 through a guide roller 104. Reference numeral 106 denotes a film guide for guiding the film 103 along a predetermined traveling path; and 107, a pressure plate that holds the film 103 between itself and the film guide 106 and supports a magnetic head 109 for recording or reproducing information so as to make the magnetic head 109 come into slidable contact with the film 103. This pressure plate 107 is elastically supported on the camera body through a pressure plate spring 108.
As shown in FIGS. 9 and 10, the magnetic head 109 for reading/writing magnetic information from or on the film 103 is placed on the pressure plate 107 at a position corresponding to an end portion of the film 103 in the longitudinal direction. Although the location of the magnetic head 109 varies depending on the design of a magnetic storage portion, the magnetic head 109 is located to record or reproduce photographing information in units of frames of the traveling film 103 at a predetermined timing.
When the magnetic head 109 is mounted on the pressure plate 107, a window portion 107a is formed in the pressure plate 107 at a predetermined position, and the magnetic head 109 is exposed to a magnetic storage portion 103a of the film 103, as shown in FIG. 10. At this time, the magnetic head 109 is fixed to the pressure plate 107 with a high precision in terms of the track position, azimuth, and positions in the roll/pitch directions so as to come into slidable contact with film 103.
A pair of guide rods 112 and 113 for helping the film 103 travel and in positioning it to project from the pressure plate 107 toward the film 103 to guide an edge 103b of the film 103.
FIG. 11 shows a general magnetic head element. FIG. 12 shows a magnetic head incorporating the general magnetic head element.
The magnetic head 109 described above has an arrangement like the one shown in FIGS. 11 and 12 and is formed in the following procedure. Magnetic core halves 120 are formed by stacking and joining a plurality of substantially C-shaped core half elements 120a formed by punching or the like using thin magnetic plates (e.g., permalloy or high-hardness permalloy). Surfaces of the magnetic core half 120 between which magnetic gap is to be formed are polished/lapped to form butt surfaces. Thereafter, a coil bobbin 122 having a coil 123 wound therearound is mounted on the rear portion side, and the pair of magnetic core halves 120 are joined to each other to face each other through a nonmagnetic member 121 serving as a magnetic gap, thereby forming a magnetic head. A magnetic head is generally formed in this manner.
The magnetic head formed in this manner is directly mounted in a holding case 125 or mounted in a holder (not shown) and an adhesive is charged into the holder. Thereafter, the film traveling surface is polished/lapped in the form of a curved surface, thereby obtaining a magnetic head 109.
Terminals 124 for electric connection to an external circuit, which are known parts of a conventional magnetic head, may be integrally formed with the coil bobbin 122 described above, or may be formed upright on the holding case and the coil 123 may be connected to the terminals 124.
In a case of a magnetic head having a reproducing function, to prevent the influence of noise from a motor and the like around the magnetic head, the holding case 125 is preferably a shielding case made of a magnetic material.
Demands have arisen for a reduction in the size of the above camera capable of recording or reproducing magnetic information, and hence a thinner pressure plate incorporating a magnetic head has been required.
Demands have also arisen for a reduction in the cost of a camera (a camera in this specification includes a so-called lens-mounted film in this specification) which is capable of recording or reproducing magnetic information and hence capable of recording information such as date. Consequently, a reduction in the cost of parts to be used for such a camera has been required.
In a magnetic head, if cores are formed by stacking a plurality of thin magnetic plates, the part cost increases. In addition, when core half elements are mated with each other, variations in thickness of each core formed by stacking thin magnetic plates varies or a track offset occurs. For this reason, when the magnetic head is positioned in the pressure plate, track position adjustment is required, resulting in an increase in assembly cost. Furthermore, when each core is formed by stacking thin magnetic plates, the surfaces that come into contact with the gap spacer as a magnetic gap cannot be made flush with each other unless they are polished/lapped. For this reason, when the magnetic head is mounted in the holding case, it is difficult to position the magnetic head at the same position in the holding case. Furthermore, since such size variations cause variations in gap position and azimuth precision, many adjustments are required to accurately position the magnetic head on the pressure plate, resulting in an increase in assembly cost.
An azimuth precision below +30.degree. is required according to the specifications. In consideration of various variations, a camera may pose a problem unless it is assembled within this tolerance. For this reason, when a magnetic head is mounted in a pressure plate, adequate adjustments are required.
Moreover, with a reduction in the size of a camera, parts, e.g., a motor used for the camera, serving as noise sources for the magnetic head are mounted near the magnetic head. Demands have therefore arisen for a magnetic head that can sufficiently resist various types of noise.